Genetic Engineering & Biotechnology News

SEP15 2017

Genetic Engineering & Biotechnology News (GEN) is the world's most widely read biotech publication. It provides the R&D community with critical information on the tools, technologies, and trends that drive the biotech industry.

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30 | SEPTEMBER 15, 2017 | CO N T I N U O U S B I O P R O C E S S I N G Dennis C. Annarelli, Ph.D., and Joshua Huang Measurements such as pressure, tem- perature, conductivity, and UV absor- bance for in-line analysis in single-use formats have been used in biophar- maceutical development and manu- facturing for many years. These mea- surements align with other single-use technologies such as bags, tubing, and filters to form complete assemblies. The availability of single-use sensors is necessary to drive implementation of single-use technology from develop- ment through to GMP manufactur- ing. Single-use sensors have gained widespread acceptance by offering the same benefits, ease of use, and con- venience as other single-use assembly components, while providing the ac- curacy and robustness of traditional measurement techniques. Stating that a sensor is single-use should not imply it is not robust. The term single-use is more related to product design, cost, and manner of use. The design of single-use sensors should be such that the costly sensing electronics are reused as extensively as possible. This can be effectively ac- complished by housing the electronics of the sensor in its monitor or trans- mitter instead of within the single-use sensor itself. By designing in this way, the cost of the sensor can be opti- mized by minimizing how much of its components are disposed. Finally, how the sensor is used will impact its design. Single-use sensors cannot be calibrated in line the way tradi- tional gauges can be calibrated, since single-use systems are not amenable to the introduction of potentially contaminating fluids into the flow path. However, single-use sensors are manufactured under tight tolerances and with repeated testing for accura- cy during their manufacture. In some cases, a calibration constant can be determined for a single-use sensor (conductivity, flow) and entered into a suitable monitor. Otherwise, single- use sensors must be used knowing that calibration is not required, or even possible. Materials of construction used in the flow path of single-use sensors provide another level of robustness for single-use sensors. Highly durable and chemically inert plastics such as polysulfone and polycarbonate comprise the bulk of the flow path in most single-use sensors. Other materials commonly used in flow paths include stainless steel and glass, where required. All single-use sensors must also meet the requirements of biocompatibility, bioburden reduction treatments, and the long-term storage stability necessary for practical adop- tion of the sensors by the biopharma- ceutical industry. The growth of continuous process- ing in biopharmaceutical manufac- turing, coupled with the benefits of single-use technology (SUT), create demand for SUT sensors that have a proven performance record for long- term use. The challenges for SUT sensors in continuous bioprocessing include the time in process for a sen- sor when the continuous process has a long duration (i.e., as seen in a per- fusion bioreactor), and whether the materials are durable enough to be exposed to process fluids for long pe- riods of time. Additionally, the sens- ing elements cannot be susceptible to drift/change over time and must Single-Use Sensors in Continuous Bioprocessing New Sensors Are Robust, but Are Still Disposable Single-use sensors represent robust technologies that can be considered for qualification in GMP processes...and are well positioned to support the growing interest in the implementation of continuous bioprocessing.

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